The purpose of this thesis is to study the origin of Japan's modern navy, the history of which began when the ruling Tokugawa Bakufu (Shogunate) opened a naval training school at Nagasaki in 1855. The thesis is therefore concerned primarily with this school, the Nagasaki Naval Training School. From the very beginning, the Dutch, as the only Europeans in Japan in those days, were involved as promoters of the School. The earliest Dutch suggestion that the Bakufu look to the improvement of Japan's defenses was made in 1844 by a delegate who brought a royal letter from King William II to the Shogun. The Dutch King in his letter advised the Japanese to open the country to the world. Again in 1852, prior to the visit of Perry, the Dutch government dispatched an envoy on a steamer, warning of imminent dangers for Japan. The presence of the well-armed steamer worked as a demonstration of modern naval power for the Japanese. After Perry's naval mission of 1853, responding to the Bakufu's request, the Dutch actively made suggestions for the creation of a modern Japanese navy. They initiated the idea of the School and took the responsibility for naval training. The first half of the thesis tries to answer the question why the Dutch worked hard for the creation of a modern navy for the Japanese in the mid-1850 's by presenting Dutch activities in diplomatic negotiations with the Japanese. The argument among some interested Japanese over the issue of national defense is also discussed, since the Bakufu's decision to build a modern navy was one of the responses that the Japanese made to the enforced opening of Japan's doors to the world in 1853. The Nagasaki Naval Training School provided not only Bakufu samurai students but also local domain students with opportunities to pursue systematic Western-style naval training. The students gradually overcame language and other barriers and learned various modern naval skills and marine technology and organization. Under the guidance of Dutch instructors, the Bakufu built a factory for the repair of naval ships as a part of the School's supporting facilities. This was the first modern factory in Japan utilizing machinery from Europe. In spite of successful operation, the Nagasaki Naval Training School was closed in the spring of 1859. The decision to terminate the School was made for political reasons, arising from the Japanese side as well as from the Dutch side. While the Dutch feared that the other Western powers would suspect that they were helping the Japanese accumulate naval power to repulse Westerners, the Bakufu became reluctant to give samurai from traditionally anti-Bakufu domains opportunities to learn modern naval technology. These anxieties coincided in the second half of 1858 and finally brought the School to an end. Although the School was short-lived, it had considerable direct and indirect influence on Japanese society. The School educated many naval officers and engineers who would later become not only founders of the Japanese Imperial Navy but also promoters of Japan's shipbuilding and other industries. A medical school with the first Western-style hospital, started as a part of the Nagasaki Naval Training School, contributed to the education of many medical doctors. Both Bakufu and local domain samurai were sent to the School, and through naval training, they got acquainted with each other. They gradually became aware of the integrity of Japan as a country among other nations, a notion which tended to supplant their exclusive concern with their origins in Bakufu or other domains. The thesis concludes that while many young men from the School became leaders of the new society after the Meiji Restoration of 1868, various facilities built for the School provided Meiji Japan with a valuable industrial inheritance.